Adenocarcinoma — Glandular Tissue Cancer

Adenocarcinoma develops when genetic alterations disrupt the normal regulatory mechanisms of glandular epithelial tissues. Epithelial cells cover internal organ surfaces and form glands that produce and release physiological fluids. When these cells undergo malignant transformation, they proliferate autonomously, lose normal cellular architecture, and eventually acquire the ability to invade surrounding structures and enter lymphatic or vascular channels.

Under microscopic examination, adenocarcinomas typically display distinct architectural characteristics, such as tubular, acinar, or papillary structures reminiscent of normal secretory glands. Pathologists classify these tumours by their degree of differentiation, ranging from well-differentiated forms that closely mimic healthy glands to poorly differentiated tumours displaying high cellular atypia. Immunohistochemical staining and molecular testing are routinely used to confirm glandular origin and identify specific driver mutations.

Knowing that a tumour is an adenocarcinoma gives your clinical team an essential foundation for staging, treatment planning, and prognostic assessment. Because adenocarcinomas arise from specialised secretory cells, they frequently express specific cell-surface receptors and harbour actionable genetic alterations that respond to targeted drugs. Furthermore, identifying an adenocarcinoma in a metastatic lesion helps pathologists locate the primary tumour through organ-specific marker testing. This classification guides choices regarding surgery, cytotoxic chemotherapy, immunotherapy, and molecularly targeted therapies.

Diagnosis requires a tissue biopsy, which is examined by a pathologist using light microscopy. Glandular differentiation is confirmed using special histochemical stains (such as mucicarmine) and immunohistochemical markers including cytokeratins (CK7, CK20), TTF-1, CDX2, or PSA. Once tissue architecture is verified, molecular testing via next-generation sequencing often identifies actionable alterations, such as EGFR mutations, ALK rearrangements, or KRAS variations.

Adenocarcinomas can develop in almost any glandular organ. They account for nearly all colorectal, prostate, and pancreatic cancers. They also represent the majority of breast malignancies (arising in ductal or lobular epithelium), the most common subtype of non-small cell lung cancer (especially among non-smokers), and most gastric, oesophageal, and endometrial cancers. Treatment strategies differ substantially depending on the primary organ of origin.

Management of adenocarcinoma depends on the anatomical site and clinical stage. Early-stage tumours are generally treated with surgical resection, occasionally preceded or followed by adjuvant therapy. In advanced stages, systemic treatments dominate care. Many adenocarcinomas are amenable to targeted therapies, such as EGFR inhibitors in lung adenocarcinoma or HER2-directed monoclonal antibodies in breast and stomach adenocarcinomas, alongside conventional chemotherapy and immune checkpoint inhibitors.